Not sure what you mean by block changing.
Skipping to non-adjacent gears (eg 1 to 3) rather than purely squentially. I do this all the time.
I got told off during an advanced driving session given by a police trainer for not using engine braking but braking and block changing down when approaching a junction.
That is the way driving is taught these days: brake without changing gear (clutch when necessary), only select the appropriate gear whan about to pull away. The theory is that brake pads are consumables, gearboxes are not. Using engine braking was appropriate before disc brakes were commonplace, the old drum brakes not being very efficient and (worse) likely to suffer fade.
A little unfair as I used engine braking when in staccato traffic but which had the disadvantage of not alerting the driver behind I was slowing as there were no brake lights.
When going down the gears for deceleration, this should be in conjunction with brakes and not instead of. The "dropping a cog" I was talking about (eg for "enthusiastically" taking bends) is not for deceleration but for the fine feathering available on the throttle to maintain the balance of the vehicle in the bend. Any slowing down will have been on the approach to the bend and not during it.
Yes, your typical copper is not an exemplary driver (and in my opinion neither do they have a full grasp of the law). Recently I was following a marked police car and it went through a red light. I gave it the benefit of the doubt that it might have been in a hurry, but I caught it up again a while later. I considered submitting my dashcam footage to the police portal, but decided against (I might have become a marked man!).
A major irritation is the way EVERYBODY (except me) sit on their footbrakes when stationary, dazzling those behind with their brake lights. Apply the f***ing handbrake you lazy f***ers!!! Even the sodding police. Even when a hill start will be required so they'll have to use the handbrake anyway. Except... modern cars make it awkward to do that (as I discovered in an electric Mokka), and those which have automatic handbrakes seem to leave the brake lights on when the automatic brake is applied, so...